Spherical shape hydroxyapatite powders prepared by flame spray pyrolysis

Micrmetre-sized HA powders with dense or porous morphologies were prepared by flame spray pyrolysis from a spray solution with citric acid and ethylene glycol. The powders prepared by high temperature flame spray pyrolysis had hexagonal-dipyramidal structures of HA regardless of the flow rates of the carrier gas. When the carrier gas flow rate was 20 Lminute^-1, the powders prepared had a micrometre size, spherical shape and dense morphology. The mean size of the HA powders with a spherical shape and dense morphology was 1.1 μm. However, the powders prepared at high flow rates of carrier gas above 30 Lminute^-1 had sizes of several micrometre and porous morphologies. The composition ratio of calcium and phosphorous components of the HA powders with a spherical shape and dense morphology was 1.69. The morphology of the micrometre-sized powders with a spherical shape and dense morphology was maintained after post-treatment at a temperature of 900 °C.